Photographic emulsions and solutions containing silver salts of thioglycolic derivatives



United States Patent PHOTOGRAPIHC EMULSIONS. AND SOLUTIONS CONTA NING SILVER SALTS, 0F THI GL COLIC DERIVATIVES Henry C. Yutzy and Albert W. Wise, Rochester, N. assignors to Eastman Kodak Company, Rochester,

N. Y., a corporation of New Jersey No Drawing. Application June 21, 1955 Serial No. 517,092

6 Claims. (Cl. 96-96) out of one of the steps of processing exposedv silver halide emulsion in the presence of a thioglycolic amide derivative. The method described therein is effective for that purpose but in the case of some types of silver halide emulsions desensitizing of the emulsion may occur when compounds of the type mentioned therein are contacted with the silver halide for extended periods.

One object of our invention is to provide a method of preventing plumniing of photographic silver images without decreasing the sensitivity of the silver halide emn'lsity obtained is consistently better than the correspondingmaximum density when these compoun are Omitted or when the free compounds corresponding thereto are incorporated in the emulsion layer or in coating layers adjacent to the photographic emulsion layer. Compounds whose silver salts are useful in products in accordance with our invention are described in U. S. Patent 2,5 3,861 o weis berg r of Ap i 1 5 he o pounds in accordance with our invention, are employed at the rate of 0.5-3 grams of silver salt per mol of silver halide contacted in accordance with our invention.

The following examples illustrate our invention.

Example 1 Finely dispersed silver chloride was prepared by adding a solution of 5.44 grams of silver nitrate in 95 ml. of water and a solution of 2.24 grams of potassium chloride in 95 ml. of water simultaneously to 200 ml. of 5% gelatin solution at 40 C. with stirring. 'The silver salt of 2-thioglycolylamidobenzothiazole was formed by mixinga solution of the sodium salt thereof (which had been prepared by dissolving 2.6 grams of 2-acetylthioglycolylarnidobenzothiazole in 14 ml. of 2.5 N. sodium hydroxide with 25 ml. of additional water) with the silver chloride preparation. The thus prepared silver salt was added to a gelatino-silver chloride emulsion containing about 2% silver bromide, in one case in the proportion of 0.7 gram of the silver salt of acetylthioglycolylamido'bengothiazole per mol of silver halide and in the second case in the proportion of 2.8 grams thereof per mol of silver halide in the emulsion. Solutions of saponin and formaldehyde were also added to each sample of emulsion and they were coated on a single weight baryta coated paper at the rate of 1 mol of silver per 1000 sq. ft.

sion from which they are derived. Another object .of our invention is to employ certain simple salts to give the antiplumming effect. A further object of our inventionto provide antiplumming agents which may be directly ncorporated in the photographic emulsion or in layers in contact therewith without itesof. the photographic emulsion. Other objects of our invention will appear herein.

We have found that the silver salt of 2-thioglycolylamidobenzothiazole and the silver salt of 2-acetylthioglycolylamidobenzothiazole are both excellent antiplummmg agents either when added to the photographic emulsion prior to applying to a support orwhen incorporated in a gelatin solution which is applied as an overcoating over the photographic emulsion layer. We have found that the tendency of thioglycolic acid derivatives to desensitizc fast emulsions is eliminated by using the S lver salts in contact with the photographic emulsion either by incorporating therein or by incorporating in layers in contact with photographic emulsion layers.

any efiect upon the proper- Our invention involves the reacting of silver nitrate The product was exposed, developed, fixed and washed and test strips were dried at approximately F. on a Kodak gloss print drier. The results obtained as compared with the same emulsion having no antiplumming agent therein were as follows:

- Maximum Concentration of anti-plummlng agent-grams .per density after mol of silver drying at Example 2 A sodium salt of thioglycolylamidobenzothiazole was prepared by dissolving .005. mol of acetyl thioglycolylamidobenzothiazole in 2.5 normal NaOl-I. The sodium salt was added to a solution containing 5 grams of gelatin, 10 ml. of 7.5% saponin and suificient water tomake 313 ml. There was then added thereto with stirring a silver nitrate solution containing 0.74 gram silver nitrate, 5 grams, gelatin, 10 ml. of 7.5% saponin and sutiicient water to make 312 ml. There was thereby obtained a suspension of silver salt in aqueous gelatin. This material was coated over a gelatino-silver chloride emulsion containing 2% silver bromide at rates equivalent to 2.0, 5.5 and 15 mg. of the silver salt of thioglycolylamidobenzothiazole per sq. ft., the emulsion layer being present on the paper at the rate of 1 mol of silver per 1000 sq. ft. After drying, the photographic product thus obtained was exposed, developed, fixed and Washed and test strips were dried at F. on a Kodak gloss print drier. The effectiveness of the silver salt in supfixation and washing, test strips were dried at approximately 290 F. The results obtained in the 2 cases are as follows:

nu n i i ii 5 o t tainin n 1 u ti ii Concentration of anti-plumming agent,M grams ensi y er vercoa con gea vc ens y per Sq. Ft. or grams per mol of AgX Dgsi pi at Speed grgylmg 1. 74 Sodium salt 0. 25 l. 25 2.00 Silver salt 1.0 1.30 2.12 g. 10 we The antlplummmg agents in accordance with our in- AgX being silver halide; vention may also be employed in layers which are first Example 3 laid down on the paper support such as baryta-gelatin.

A silver salt of acetylthioglycolylamidobenzothiazole was prepared by dissolving 0.675 g. thereof in 100 ml. of methanol, mixing with 187 grams of 6.6% gelatin solution plus sufiicient water to bring the total volume to 375 ml. and mixing the whole with a second solution of 44 ml. of 1% silver nitrate solution, 187 ml. of 6.6% gelatin solution mixed with sufficient water to bring the total volume to 375 ml. The solution of silver nitrate was added quickly and with stirring to the solution of acetylthioglycolylamidobenzothiazole.

The silver salt in gelatin solution thus prepared was applied over a gelatin silver chloride emulsion layer on single Weight baryta coated paper base at a rate equivalent to 7.5 mg. of the silver salt of acetylthioglycolylamidoben zothiazole per sq. ft.,the emulsion coating being at the rate of approximately 1 mol of silver per 1000 sq. ft. Another application of the silver salt at the rate of 3.75 mg. per sq. ft. was made by first diluting the solution of gelatin and silver salt with an equal volume of 3.3% gelatin solution. These products were exposed and were developed, fixed and washed. Test strips of this photographic material were dried at 180 F. on a print drier and the table indicates the comparison of the maximum density of the product as compared to one in which the antiplumming agent was not supplied.

Maximum Concentration of silver salt nntlplumming agent density after hot ierrotyp- 0 l. 73 3.75 mg. per sq. ft. or 3.75 g./mol Ag 1.96 7.5 mg. per sq. ft. or 7.5 gJmol AgX 2. ll

AgX being silver halide.

Example 4 The silver salt of thioglycolylamidobenzothiazole causes no desensitization when material containing that layers and the emulsion is applied thereover. Our invention is especially adapted for use in connection with photographic emulsions employed for photographic paper purposes in which drying at elevated temperatures occurs.

We claim:

1. A photographic element comprising a silver halide emulsion layer, containing as an additive thereto an antiplumming agent selected from the group consisting of the silver salt of thioglycolylamidobenzothiazole and the silver salt of acetylthioglycolylamidobenzothiazole.

2. A photographic element comprising a silver halide emulsion layer containing as an additive thereto a sulficient proportion therein of a compound selected from the group consisting of the silver salt of thioglycolylamidohenzothiazole and the silver salt of acetylthioglycolylamidobenzothiazole to prevent plumming of the photographic image formed therefrom.

3. A photographic element comprising a silver halide emulsion layer and in contact therewith a water permeable colloid layer containing as an additive thereto an antiplumming agent selected from the group consisting of the silver salts of thioglycolylamidobenzothiazole and the silver salts of acetylthioglycolylamidobenzothiazole.

4. A photographic silver halide emulsion containing as an additive thereto the silver salt of thioglycolylamidm benzothiazole in suflicient amount to prevent plumming of the photographic image which is formed by the emulsion.

5. A photographic silver halide emulsion containing as an additive thereto the silver salt of acetylthioglycolylamidobenzothiazole in sufficient amount to prevent plumming of the photographic image which is formed by the emulsion.

6. A coating composition comprising an aqueous solution of gelatin containing as an additive thereto a compound selected from the group consisting of the silver salts of thioglycolylamidobenzothiazole and of acetylthioglycolylamidobenzothiazole.

References Cited in the tile of this patent UNITED STATES PATENTS 2,214,446 Albers et a1. Sept. 10, 1940 2,432,865 Dimsdale et al Dec. 16, 1947 2,657,135 Lowe et al Oct. 27, 1953 FOREIGN PATENTS 436,576 Great Britain Jan. 6, 1934 484,595 Great Britain May 9, 1938 699,858 Great Britain Nov. 18, 1953 708,065 Great Britain Apr. 28, 1954 

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SILVER HALIDE EMULSION LAYER, CONTAINING AS AN ADDITIVE THERETO AN ANTIPLUMMING AGENT SELECTED FROM THE GROUP CONSISTING OF THE SILVER SALT OF THIOGLYCOLYLAMIDOBENZOTHIAZOLE AND THE SILVER SALT OF ACETYLTHIOGLYCOLYLAMIDOBENZOTHIAZOLE. 